Since their initial discovery in 1957, interferons, originally described as factors that interfered with viral infection, have been widely studied. Interferons (IFNs) are now recognized as an integral part of the body's natural defense system, and they are used successfully as therapeutic agents for the treatment of a number of human diseases. IFNs are segregated into two classes defined as either type I or type II. Type I IFNs include a family of related proteins, IFNα, IFNβ, IFNω, IFNτ and IFNδ, whereas type II IFN consists of one protein, IFNγ, which has limited homology to type I IFNs.
Two receptor proteins, IFNAR1 and IFNAR2 are known to be involved in type I IFN binding.